INTRODUCTION 17 



may only attempt to resolve the aggregate into 

 its simpler components in a logical way. The cell, 

 the simplest unit now available as a living thing, 

 is, itself, complex, and when it lives in the free 

 state it is scarcely less so than other organisms. 

 The simplest multicellular organism seems much 

 more intricate but it accomplishes the same ends 

 as its simpler brother; its elaborate structure is a 

 matter of method rather than result. All living 

 things of the present share this quality, hence the 

 heritage, that which reacts with the environment 

 in the maintenance of the phenomenon called life, 

 is complex in proportion to the degree of self- 

 determination that it has wrested from its sur- 

 roundings and in relation to the nature of its ul- 

 timate dependence upon them. 



The details of organic complexity are, as has 

 been said, the substance of biological science. It 

 is characteristic of past treatment of evolution 

 that we have recognized their importance in the 

 existence and transformation of living things even, 

 in many cases, to the exclusion of any serious con- 

 sideration of the other factors necessary to their 

 existence, namely, environmental conditions. But 

 we cannot expect to understand the organism or 

 its evolution without giving adequate attention to 

 every significant fact. 



The complexity of the environment is no less 

 than that of the organism, but certain of its char- 



